The invention relates to an apparatus and method for winding a web of tapes or yarns into a plurality of packages.
It is known to produce film tapes from thermoplastic high-polymer plastics for various uses with the therefor required specific product properties. Such uses include, for example, tapes for weaving carpet backings, or for packaging fabric, film tapes for producing twines, cords, or ropes, as well as film tapes as a raw material for splicing yarns and similar products.
In the known extrusion lines, plastics are plasticized in a continuous process, and extruded in the molten state as an endless film by a die, preferably a wide-slot die. This endless film is quenched in a tempered cooling bath to below the softening point of the plastic. After cutting the edges of the endless film, the flat film is divided into a web of narrow, flat tapes, which are monoaxially drawn in a lengthwise orientation between arrangements of rolls or godets, which are designed and constructed preferably as draw units looped by the tapes, and between which hot-air ovens are arranged.
The narrow, flat tapes are wound into respective packages by means of a winding device. As is disclosed, for example, in DE 34 14 636, after leaving the last godet, the web of narrow tapes advances over a yarn guide bar which mounts a plurality of yarn guides, before the individual tapes of the web are distributed to individual winding positions. The winding positions extend along a long side of the machine. To distribute the film tapes, the web of tapes advances in a plane above the winding positions. In each winding position, a tape is wound to a cross-wound package. At the time the package mounted on a winding spindle has reached its intended size, it becomes necessary to doff the package. To this end, the tape is cut and advanced to waste by means of a suction gun. The package is removed from the winding spindle and replaced with an empty tube. Subsequently, the tape is threaded on the empty tube to wind a new package. The package doff is carried out manually. Thus, the known apparatus is suitable only to produce packages with a relatively low weight.
It is therefore an object of the invention to further develop an apparatus and a method of the initially described kind such that it is possible to wind and doff packages of a greater weight, in particular greater than 12 kg.
The invention distinguishes itself in that it permits doffing the packages in the winding positions with the use of an auxiliary device, which is adapted for unimpeded movement in a doffing plane, which extends parallel to the long side of the machine. In accordance with the invention, the web of slit-film tapes advancing crosswise to the long side of the machine is guided out of a distribution plane for purposes of doffing the packages, so that none of the slit-film tapes traverse the doffing plane. To this end, the yarn guide bar upstream of the winding positions is made movable. Thus, the yarn guide bar is moved out of its operating position only for doffing the packages, in order to deflect the web of slit-film tapes.
According to an advantageous further aspect of the invention, the movement of the yarn guide bar is performed by a drive at a uniform guiding speed. This ensures that no sudden fluctuations in the yarn tension can occur, so that during the movement of the yarn guide bar, winding of the slit-film tape can continue unimpeded.
To be able to perform the movement of the yarn guide bar with simple means, an advantageous further feature of the invention provides that one end of the yarn guide bar is designed and constructed as a pivot bearing. In this instance, a pivot drive pivots the yarn guide bar crosswise to the direction of the advancing yarn. Preferably, a stop is used to define the operating position of the yarn guide bar and its deflected position.
To ensure a great flexibility in winding the slit-film tapes of the web, a preferred further feature of the invention provides that in each winding position the auxiliary device traveling in the doffing plane doffs the packages, one after the other. Preferably, the auxiliary device is formed by a package manipulator arranged on an overhead conveyor. Thus, the package manipulator is used to remove only the full package from the winding spindle of the winding position and to transport the full package, for example, to an adjacent creel.
Since the looping of the individual slit-film tapes of the web changes in the deflected position of the yarn guide bar, a further advantageous feature provides that the yarn guide bar is equipped with a plurality of yarn guides, which each comprise a guide edge partially surrounding the tape for guiding it. This ensure a reliable guidance of the slit-film tapes of the web in each position of the yarn guide bar.
To wind as many tapes or yarns as possible to packages with one device, the winding positions are arranged in a plurality of horizontal rows, one below the other along the long side of the machine. The yarn guides associated to the winding positions for distributing the tapes or yarns extend above the uppermost horizontal row, so that a deflection of the yarn guide bar with the web of tapes or yarns does not affect the distribution to the individual winding positions.
In the cases, wherein the winding positions extend along two long sides of the machine that adjoin in mirror symmetry, a movable yarn guide bar is associated according to the invention to each long side of the machine. This permits doffing packages in winding positions on one long side of the machine independently of the takeup positions of the adjacent long side of the machine.
Preferably, the yarn guide bars are moved independently of each other by means of separate drives at a uniform guiding speed.
In a particularly advantageous further feature of the invention, each winding position is provided with a compensating arm control for purposes of winding the tapes or yarns to a package under a substantially constant tension. Thus, in the winding positions, a change in the tension caused by the different looping in the deflected position of the yarn guide bar, is completely controlled, so that the package can be wound under the same tension.
To ensure an undisturbed advance of the web of slit-film tapes in the components of the extrusion line upstream of the takeup device, a further advantageous feature of the invention comprises a depressor arranged upstream of the yarn guide bar. The depressor guides the web of slit-film tapes in a plane, which enables an undisturbed advance from upstream machine components.